Spall lime kiln



Dec. 8, 1936. c ARNOLD I 2,063,219

SPAIJL LIME KILN Filed Feb. 15, 1936 2 Sheets-Sheet 1 Zlnwcnioc CHARLES F. ARNOLD duo: new a Dec. 8, 1936. ARNOLD 2,063,219

SPALL LIME KILN Filed Feb. 15, 1936 2 Sheets-Sheet 2 CHARLES ARNOLD Patented Dec. 8, 1936 UNHTED STATES PATENT OFFIQE 5 Claims.

The invention relates to kilns for burning lime rock and it aims to provide a new and improved kiln for advantageouslyburning spall, that is, limerock in relatively small pieces ranging from three-fourth inch to four inches, the usual lime kilns being unsuitable for handling the rock in such small pieces.

With the foregoing in View, the invention resides in the novel subject matter hereinafter described and claimed, description being accomplished by reference to the accompanying drawings.

Figures 1 and 2 are vertical sectional views in planes at right angles to each other.

Figure 3 is a horizontal sectional view on line 33 of Fig. 1.

Figure 4 is a horizontal section on line 4-4 of Fig. 2.

A preferred construction has been shown and will be rather specifically described, with the understanding however, that within the scope of the invention as claimed, variations may be made.

A stack 5 is provided of suitable masonry, lined with suitable fire-resisting material as shown at 6, the stack being supported by an appropriate frame structure or the like 1.

Between its ends, the stack 5 is provided with a portion 8 of rectangular cross section internally, substantially one-third of the length of said stack being below said portion 8. At its upper end, the stack is of inverted frusto-conical internal cross section as disclosed at 9, and the lower end it of said stack is of internal circular cross section. The stack portion it between the portions 9 and 8 is of a cross section which gradually changes from circular where it joins said portion 9, to rectangular where it joins said portion 8. Similarly, the stack portion 52 between the portions 6 and 8 is of an internal cross section which changes gradually from circular at its lower end to rectangular at its upper end. The stack portion ll constitutes a combustion chamber which is shorter and more contracted than the corresponding combustion chamber of a conventional lime kiln, and the stack portion !2 which constitutes a cooling chamber, is from two to three times as long as in the conventional lime kiln, insuring such effective cooling as to overcome possibility of crystallizing the product. The circular cross section of the stack on the plane at which the portions 9 and H join each other, is of a diameter longer than the shortest horizontal dimension of the rectangular portion 8 and shorter than the longest horizontal dimension of said portion 8, whereby the sides of said portion H converge downwardly to the opposed vertical side walls of said portion 8 (Fig. 1) and diverge downwardly to the opposed vertical end walls of said portion 8 (Fig. 2) Similarly, the lower extremity of the stack is of an internal diameter shorter than the longest horizontal dimension of the portion 8 and longer than the shortest horizontal dimension of said portion 8, whereby the sides of the cooling chamber I2 diverge downwardly from the opposed sides of said portion 8 (Fig. 1) and converge downwardly from the ends of said portion 8 (Fig. 2)

The stack 5 is provided with opposed fire-holes or eyes It which open through the opposite side walls of the rectangular portion 8, and any desired means may be provided for supplying flame and products of combustion to the stack through said fire-holes or eyes. In the present disclosure, fire-boxes i i are provided, grates l5 being shown in said fire-boxes for burning solid fuel, although oil or gas burners could of course be employed if desired.

spall-splitting arches l5 preferably formed from carborundum extend transversely across the stack and have their ends joined to the opposed side walls of the portion 8, immediately above the fire-holes or eyes it, said arches l6 being entirely above said fire-holes l3, leaving the latter unobstructed in case it should be necessary to insert a poker, slice bar or the like through said fire-holes to loosen the material in the kiln. These arches split and loosen the mass of spall and insure that the flame and combustion products can properly enter the mass toact thereon, the distribution of flame and gases being much more even than could otherwise be attained.

The bottom walls i! of the fire-holes or eyes [3 are shorter than the top and side walls thereof, and the stack is provided with inclined wall portions 58 which diverge upwardly to the inner ends of said bottom walls ll, providing a structure which effectively prevents the spall from lodging upon the walls ll, as would otherwise occur.

The kiln is charged through its conical upper end 9, is fired for a proper time and is then drawn, its lower end being provided with suitable means such as a hopper iii and gate 25 for drawing purposes. As the burnt lime is withdrawn from the lower end of the kiln, the spall gravitates within the stack and more spall is added at the top. Should any of the spall lodge upon the arches it, it may be loosened by inserting a poker or the like through the fire-holes or eyes l3.

By providing the novel construction shown and described or a substantial equivalent thereof, I provide an improved kiln for effectively burning spall. The flame and products of combustion being centrally introduced into the spall, a more even distribution and better burning takes place, and due to the exceptionally large cooling chamber, crystallization of the product cannot occur. The construction allows perfect control of drawing of the kiln and as the material descends therein, there is no danger of any of said material lodging in the fire-holes or eyes. This latter result is attained partially by the short bottom walls I! of the eyes or holes I3 and the associated wall portions 18 of the stack, and partly by the relation of the arches I 6 with said fireholes or eyes.

As excellent results are obtainable from the general construction shown and described, it is preferably followed. However, within the scope of the invention as claimed, variations may be made.

I claim:-

1. A spall lime kiln comprising a stack of rectangular internal cross section between its ends, of inverted conical internal cross section at its upper end, of circular internal cross section at its lower end, and of an internal cross section gradually changing from circular to rectangular from said ends to said rectangular portion, the portion of said stack above said rectangular portion constituting a combustion chamber, the portion of the stack below said rectangular portion constituting a cooling chamber, opposite side walls of said rectangular portion being provided with fire-holes, spall-splitting arches across the stack and extending between said side walls immediately above said fire-holes, said arches being disposed entirely above said fireholes, and discharge controlling means at the lower end of the stack.

2. A spall lime kiln comprising a stack of rectangular internal cross section between its ends, of inverted conical internal cross section at its upper end, of circular internal cross section at its lower end, and of an internal cross section gradually changing from circular to rectangular from said ends to said rectangular portion, the portion of said stack above said rectangular portion constituting a combustion chamber shorter and more contracted than the combustion chamber of a conventional lime kiln, the portion of the stack below said rectangular portion constituting a cooling chamber from two to three times as long as the combustion chamber of a conventional lime kiln, opposite side walls of said rectangular portion being provided with fire-holes, spall-splitting arches across the stack and extending between said side walls immediately above said fire-holes, said arches being disposed entirely above said fire-holes, and discharge controlling means at the lower end of the stack.

3. In a spall lime kiln, a stack provided between its ends with opposed fire-holes, and a spall-splitting arch extending across said stack and having its ends disposed immediately over said fire-holes, said arch being disposed entirely above said fire-holes, the bottom walls of said fire-holes being shorter than the top and side walls thereof, the stack being provided with inclined wall portions diverging upwardly to the inner ends of said bottom walls; whereby the spall is prevented from lodging in the inner ends of said fire-holes during descent.

4. A spall lime kiln comprising a stack of rectangular cross section between its ends, sub stantially one-third of the stack length being below said rectangular portion and constituting a cooling chamber, the internal cross section of said stack being gradually changed from rectangular at the upper end of said rectangular portion to circular at a plane near the upper extremity of the stack and constituting a combustion chamber, the stack being internally of inverted frusto-conical shape from said upper extremity of the stack entirely to the aforesaid plane for charging purposes, the internal diameter of the stack at said plane being longer than the shortest horizontal dimension of said rectangular portion and shorter than the longest horizontal dimension of said rectangular portion whereby the stack sides converge downwardly from said frusto-conical portion to the opposed vertical sides of said rectangular portion and diverge downwardly from said frusto-conical portion to the opposed vertical ends of said rectangular portion, the portion of the stack below said rectangular portion being of a cross section gradually changing from circular at its lower extremity to rectangular at its juncture with said rectangular portion, the internal diameter of the stack at its circular lower extremity being longer than said shortest horizontal dimension of said rectangular portion and shorter than said longest horizontal dimension of said rectangular portion whereby the stack sides diverge downwardly from said opposed vertical sides of said rectangular portion and converge downwardly from said vertical ends of said rectangular portion, said stack being provided with fire-holes opening through said opposed. vertical sides of said rectangular portion.

5. A spall lime kiln comprising a stack of rectangular cross section between its ends, substantially one-third of the stack length being below said rectangular portion and constituting a cooling chamber, the internal cross section of said stack being gradually changed from rectangular at the upper end of said rectangular portion to circular at a plane near the upper e-xtremity of the stack and constituting a combustion chamber, the stack being internally of inverted frusto-conical shape fro-m said upper extremity of the stack entirely to the aforesaid plane for charging purposes, the internal diameter of the stack at said plane being longer than the shortest horizontal dimension of said rectangular portion and shorter than the longest horizontal dimension or said rectangular portion whereby the stack sides converge downwardly from said frusto-conical portion to the opposed vertical sides of said rectangular portion and diverge downwardly from said frusto-conical portion to the opposed vertical ends of said rectangular portion, the portion of the stack below said rectangular portion being of a cross section gradually changing from circular at its lower extremity to rectangular at its juncture with said rectangular portion, the internal diameter of the stack at its circular lower extremity being longer than said shortest horizontal dimension of said rectangular portion and shorter than said longest horizontal dimension of said rectangular portion whereby the stack sides diverge downwardly from said opposed vertical sides of said rectangular portion and converge downwardly from said vertical ends of said rectangular portion, said stack being provided with fire-holes opening through said opposed vertical sides of said rectangular portion, and spall-splitting arches extending across said rectangular portion and having their ends disposed immediately above said fire-holes, said arches being disposed entirely above said fire-holes.

CHARLES F. ARNOLD. 

